Television system



Aug. 13, `1935.

figg@ B. ClOFFARl TELEVI SION SYSTEM Filed April l, 1929 lNvENToR BERNARD clon-ARI x BY A'TTORNEY Patented Aug. 13, 1935 TUNITED STATES PATENT OFFICE TELEVISION SYSTEM .Bernard Cofari, New Rochelle, N. Y., assigner to Radio Corporation of America, a corporation A subject in such systems.

of Delaware Application pril 1, 1929, Serial No. 351,488 15'` (alarms. (o1. 17a-6) The present invention relates to television systems, and, more'particularly, to. a method and means for scanning and reproducing a television In the prior art, so far as I` am' aware, it has hereinbefcre been customary to utilize, `for the purpose of scanning and reproducing, disks of rather large size in orderto provide suicient detail by which the television picture received may be readily recognized and be of considerably clearer detail. It has been found, however, with the use of such disks, which may be either of the lens or mirror type, that objectionable features have been occasioned by reason of the fact that such disks were very cumbersome and found to haveflarge moments of inertia, and were incapable of being driven by any small type of synchronous motor such as could be readily driven from the ,wr small amount of energy received over a television 20' transmission system forV the purpose of syncrornzing. With A the use of large moto-rs, such as are necessary furthe larger size disks, considerable diinculties insynchronizing have been occasioned by reason of the fact that any synchronizing action produced on the drive motor for the disk must be by way of a small synchronous motor, or similar compensating element, used to control the main `drive motor. A small motor o-f this type in order to synchronize the rotating elements of the transmitter must either exert a retarding or advancing action upon the main drive motor, and considerable difficulties have been occasioned in arranging a set up' by which this type, of synchronizing could readily be accomplished.

Also,` with the use of large disks ysuch as are necessary togam the desired amount'of detail, difficulty has4 beenfoccasi-oned Vin arranging a .l compact installation such as would be convenient loccasioned by the use of large disks for television ,scanning and reproducing are substantially eliminated. Y v A further object of my invention is to provide amethod and means for scanning and reproducing television subjects in which the rotating elements4 necessary have been materially reduced in size so that they may be driven by the smallest types of synchronous motors which, in'turn, may synchronized' by the use of a small amount of energy such as is obtainable from a synchronizing signal simultaneously transmitted with the -television.k n

A further object of my invention is to provide aV method and means forscanning television subjects which will materially reduce the installa- 5 tion expense, since the parts thereof have been reduced to a minimum, and, consequently, less expense for lenses if a lens disk be used, or mirrors, if a mirror disk be used, is necessary.

1 Still another object of my invention is to pro- 10 vide a method and means by which the speed at which the `television subject may be scanned may be considerably increased, and, thus, the objectionable eiects of iiicker in the reproduced image substantially avoided. Such arrangement is possible with a considerable reduction in the size of the moving elements which are thus capable or higher speeds, and which can be driven by smaller motors, and vby which it is possible to considerably increase the optical efliciency of the entire system. i

. Still another object of my invention is to provide a method and means for scanning and reproducing television subjects which is simple in its construction and Varrangement of parts, a system which is durable, compact, conveniently installed, readily set up, easily operated, efficient in its usej-,and readily adapted to use in conjunction with the present types of transmitting and receiving circuits and apparatus.

YStill other and ancillary objects will become apparent and at once suggest themselves to those skilled in the art to which the invention relates by a reading of the following specication taken in connection with the accompanying drawing,

wherein: Y Fig. 1 illustrates an arrangement disclosing the principle of my invention utilizing a small disk having only four reecting surfaces; n

`Fig. 2 illustrates conventionally a form of ap- 40 paratus especially suited to the purpose and arrangement of my invention;

' Fig. 3 diagrammatically illustrates a further arrangement of the invention; Fig. 4 diagrammatically illustrates the paths by 45 which the television subject is exposed to scanning rays of light, or by which the paths of light of varying intensity, controlled in accordance with the intensity of light and shadow on the television subject, may be reproduced;

Fig. A5 discloses a modification of my invention as applied to 'a-lens disk type of scanning element in contrast to the mirror disk disclosed by Figs.

arrangement of the reflecting surfaces as tilted in the vertical plane; and,

Fig. 7 conventionally illustrates the manner' in which the picture is rebuilt when using a disk and cooperating fixed mirror surfaces of the type shown by Fig. 2.

Now particularly referring to the accompanying drawing, it will be recognized that if a large size disk of the mirror type be used, for example, and a sixty line detail picture be desired, that with the type of scanning system hereinbefore used in connection with television developments, it was necessary to provide sixty distinct reflecting bodies placed about the periphery of a disk so that each successive mirror would be tipped at an angle of six degrees with respect to the preceding mirror in the plane of the disk. With such a system, supposing that sixty mirrors'are used about the disk, it will be seen that beams of light reflected from two successive mirrors will be at an angle of twelve-degrees with respect to each other, since when light is reected upon a mirror, if the plane of the mirror is rotated through a given angle, the reflected beam of light will be rotated through twice that angle. This would mean that as the disk is rotated, only twelve degrees of rotation of the beam of light reected by any one mirror is capable of utilization because of the fact that the light reflected by adjacent mirrors will follow `the light reflected by the first mirror after the first light beam has traveled through an angle of twelve degrees. Therefore, if it were possible to utilize more than a twelve degree angle of the reflected light beam, it would also be possible to reduce the size of the scanning disk element.

Now referring particularly to Fig. l, suppose, for example, that only four mirrors, I, 2, 3 and 4, were arranged about the periphery of a scanning disk;` Then, as this disk rotates in the direction shown by the arrow, and a mirror moves from the position a to the position bi, the light reected by the mirror will rotate through a wide angle, and turn from the position a to the position b'. Tc utilize the `entire angular sweep between a and b', it would be necessary to place a circular cr cylindrical screenin the path of the reflected light beams. Such a system is, of course, not particularly feasible, and even aside from this feature, only four lines on the screen would be produced. -I-owever, a simple way to surmount such a diiculty is to arrange a plurality of stationary mirrors about the arc of a circle upon which the light is reiected, and 'to so tip and vtilt the mirrors that'each mirror will reflect the light therefrom to the same screen.

To refer now more particularly to Fig. 2,' showing a preferred form of' arrangement of my invention, assuming that instead of using a disk composed of only four mirror elements, as shown by Fig. l., that the number of mirror elements were substantially increased, and, for example, as shown by Fig. 2, that these elements were increased to twelve mirrors placed about the periphery of the disk, and each tilted ata slightly different angle to the plane ofthe disk. This would mean that, as the disk is rotated in the direction. shown by the arrow, twelve distinct lilies of scanning will be produced upon a screen it positioned in the path of reflected light beams, and'since the mirrors I, 2, etc., are placed at an angle of thirty degrees with respect toeach other .thetotal angular rotation produced by each distinct mirror will cover the arc of sixty` degrees before the reflected light from the next mirror comes upon the screen. With such an arrangement, the screen would then have to be a cylindrical surface covering an arc of sixty degrees in order that there would be only one spot on the screen at any one instant, and such a system would then provide a screen covered by twelve distinct lines of scanning.

Suppose, for example, that instead of placing a screen, such as the planar dotted outline screen, in the path of the light beams which are reflected from the disk II during the rotation thereof, a plurality of narrow mirrors IZ, I3, I4, I5 and I6 each covering l2 of the 60 degrees should be placed in the path of the rotating light beam reected from the mirror surfaces I, 2, 3, etc., of the disk II. Then, as the disk II rotates the beam of light refiected from each of the mirrors I, 2, 3, etc., in sequence will sweep across the arc of a circle from point c to po-int f. So arranged, it can be appreciated that each mirror surface arranged about the arc of the circle I0 willproduce on a screen I'l" arranged to receive the light received from the mirrors a single spot of light extending from points somewhat to the right and left, respectively, of the points f and c on the viewing surface II, it being understood from Fig. 3 that mirror wheel II is positioned outside the light path from reflectors I2 to IE and screen I'I. However, if it is desired to take advantage of the principle of invention illustrated herewith and in order to produce more than l2 parallel lines oflight traced upon the screen I'I by each single rotation of the mirror wheel II (assuming that 12 mirror surfaces are provided thereon) each of the separate and individual mirrors I2, I3, I II, I5 and I6 isset and Atilted, at slightly different angles, both as regards horizontal and vertical tilting, with respect to each other so that as any one beam of light is caused to travel across the screen I1 a path of light will be traced between the points f and c as the light beam reflected from any of the elemental surfaces I, 2, 3, etc., reaches each of the individual mirrors I", I5, Ill, etc. This principle has been conventionally illustrated by Fig. 2 wherein, for example, light beam reflected from the mirror surface I to strike or impinge upon the mirror I6 Will first be reflected as it strikes the mirror surface along a path cf and this path will progressively change in the direction of the point c' on the screen I'I until the light beam strikes the point d, just prior to the instant at which the light beam from reiiector I, for example, reaches the mirror surface I5, in which case the path of reflected light will be that designated by the line dc. The light beam reflected from the mirror surface I then immeriately passes on to the next mirror surface I5 which is tilted as above described with respect to the mirror surface I6 and the light path traced across the screen I'I will be iirstalong the direction df' and as the light beam reflected from the mirror I then approaches the mirror III the light path will finally change so that it extends from the left hand edge of the mirror I5 toward the point c. These various light paths are indicated in Fig. 2 by the reference numeral corresponding to that of the mirror surface from which the light beam is reflected. In accordance with this description, for each 30 degree rotation of the mirror wheel II there will be traced on vthe screen Il ve separate light paths all extending between the points f and c.

By Fig. 4, I have shown diagranimatically, a

diagram .showing the individual'paths by which the light beams are reflected,` and referring now to Fig. 4, it will be seen that the light `beam` a as reflected by the mirror I, for example, is Widely separated from the light beam b reflected by the mirror 2, for example, and that due to the angular tilting of each of the individual mirrors composing the periphery of the disk I I about the axis of the diskV II, the reflected light beams traverse parallel paths Widely separated from each other. Y Y Y However, as the light beam reected by the disk I, for example, strikes the mirror surface I6, it is reflected back upon the screen I'I along a path designated as ai on Fig. 4, and as the same light beam` reaches the? mirror I5, itis reflected along a path a2, andas the diskV II is rotated so that the refiected light beam from the surface l has reached the mirror surface I2, the path of the reflected light beam projected towards the screen I'I, has assumed a position as after which the mirror surface 2 positioned about the pcriphery of the disk II is in the path of the projected light from the source I8', which, for example, may be a glow lamp illuminated byvincoming television signals for the purpose of` reproducing, or may be an'arc source of light, if the system is to be used as an analyzing system for transmission purposes, and the subject for transmission is then positioned at the point Where the screen II is located, and the path of light initially traced by light from the source I6 being reflected from the mirror surface 2 towards the mirror It, will bealong thepath b1, and following the example shown above in connection with the mirror Il, the successive paths of illumination of the screen I'I will be along the lines bz, b3, etc. This scanning action is then continuously repeated until the projected light from the source I8 has illuminated each and every mirror positioned about the periphery of the disk II, and after the last mirror has been turned so as to` come into the path of the light rays issuing from the source I3, the scanning or reproducingprocess will be repeated, and follow the system conventionally illustrated and "described, in connectionwith Fig. 4.

Now referring more particularly to Fig. 3, I have shown an elevation view schematically describing the system hereinabove described in connection with Figs. 2 and 4, and light from the source IS is shown as projected upon a mirror 'I located on the periphery of Uthe disk Il, and then reflected to the center mirror zI4 of` the fixed bank of mirrors, each tilted at a different angle with respect to the horizontal and vertical axis, and arranged about the arc of acircle. `It is thus seenthat the reflected beam of light from the mirror surface ofthe disk II and the fixed mirror I4 will trace a path designated, as g3 and project itself upon the screen Il.

Since a mirror disk arrangement, and a lensv disk arrangement are substantially similar and equivalent, by Fig. 5, I have shown` a lens diskv 2| mountedon shaft 22 through which light from a, similar source i8 is projected and directed along a bank of mirrors arranged similarly to those shown and described in connection with Fig. 2. As, the disk 2i rotates in the direction `of the arrow, the light beams issuing therefrom may be arranged to trace similar parallel paths across the screen Il to those shown and described in connection with thevabove named figures of the drawing. Y I

By Fig. 6 I have Ashown conventionally the relationship between the various mirrors I2,` I3,

upon the size of reproduced picture which is to be desired, but if a case is assumed where twelve rotating and ve fixed mirrors are used, and the fixed mirrors are approximately 8" away from the rotating mirrors and the size of Apicture to be produced `is about l2 x l0, the angle assumed has been found to be satisfactory, although other angles of inclination may be resorted to without departing from the spirit and scope of the invention.

` Similarly, it has been assumed that the angular direction of the mirrors I3 and I5 with respect to the `plane of mirror I4, and the angle of mirrors I2 and I6 with respect to the plane of mirrors I3 and I5 is 6.3 degrees. This value is also merely illustrative and should not be considered as limiting but has been found to be satisfactory for the above assumed case.

By Fig. 7 I have shown in a diagrammatic manner the picture which is produced according to my above escribed invention. In this ligure the lines produced by the mirror surfaces I, 2, 3, etc. of the disk II have been indicated by a corresponding number with an exponent corresponding to the mirror surface of the fixed reecting body Vfrom which the light is re-directed.

From the above description, it shouldbe understood that the system is equally adapted for use either as a transmitter scanning or a receiver scanning system, and further that the term disk as hereinafter used in connection with the appended claims should be regarded in a generic sense, and include mirror disks, spirally arranged lens disks, lens disks having both mirrors and prisms so arranged as to direct the issuing light beams along different parallel paths, and, in fact, all arrangements capable of producing like results, and I, therefore, do not desire to be limited in what modifications of the system I may make, but believe myself to be entitled to all modifications such as fall fairly within the spirit and scope of the invention as defined bythe hereinafter appended claims, wherein I claim:

Having now described my invention, what I claim and desire to secure by Letters Patent is the following: l

1. The method of scanning which consists in directing light from a light source in a single beam, continuously directing said beam along an arcuate path, consecutively reecting said beam in different planes whereby it traces a plurality of different elemental width parallel paths each covering one dimension of a picture surface which is spaced away from said arcuate path.

2. In a television system, the method of scanning which includes generating a light beam oi'. an intensity corresponding to the intensity of light and shadow on elemental areas of a television subject, directing the produced light in a single beam, sequentially projecting the light beam along a series of predetermined spaced arcuate paths, and consecutively reflecting the light beams along a plurality of different adjacent parallel planes each covering one dimension of a picture surface and each of elemental width during periods of change in the sequence of arcuate motions of the light beam.

3. In a television system, the method of scanning and reproducing which includes producing Y light beams and directing the same along a predetermined path, continuously directing the said beams along a plurality of arcuately spaced paths and successively reflecting said beam in different planes for tracing a plurality of additional paths of light along a succession of transverse sections of elemental width and a length equal to one dimension of a ield of View.

4. In a television system, means for producing light intensities corresponding to the intensities of light and shadow on elemental areas of a television subject, means for projecting said light beams along a predetermined path, a disk for continuously changing the path of said projected light beams to a plurality of spaced parallel paths, and a Xed set of mirrors for continuously deiiecting the said projected light beams along successive transverse parallel paths across one dimension of a picture surface and each of elemental width interspersed between said parallel paths produced by said initial changes in path of said light beams, and a screen positioned in the path of said last named reilected light beams for producing a visible image of the television subject.

5. In a television scanning system,V a light source, means for projecting the light issuing from said source along a predetermined path, rotating means for continuously deflecting said projected light beams along a plurality of spaced horizontal paths, means positioned in the path of said deilected light beams for successively changing the path of each of said deected light beams into a plurality of adjacent parallel paths each of elemental width and vinterspersed in a vertical plane between said iirst named group of parallel paths so as toV traverse the picture area fully in one direction, and a screen means successively illuminated by all said elemental width parallel paths of light.

6. In a television scanningk system, a light source, means for projecting the light issuing from said source along a predetermined path, a rotating diskrneans positioned in the path of said projected light beams, means provided by said disk for successively projecting said light beams along a plurality of spaced parallel paths, means iixed in position and located in the path of said projected light beams for controlling the said projected light beams and tracing the same along a plurality of parallel paths each of elemental width and across the length of the picture surface interspersed between said rst named group of parallel paths, and a screen positioned in the path of all of said reflected light beams.

7. In a television system, a light source, means for projecting the light issuing from said source along a predetermined path, a rotating disk positioned in the path of said projected light beams forcontinuously and successively reflecting said light beams along spaced parallel paths, a fixed bank of mirrors in the path of said reflected light beams for directing each separately projected light beam from said disk into a number of-distinct transverse parallel sections each of velemental width and equal tothe length of the neld Yof View, and a screen positioned in the path of the reflected light from said iiXed bank of mirrors. Y

8. In a television system, means for producing light beams of predetermined intensities, means f for projecting said light produced along a predetermined path, means for continuously changing the path ofsaid light beams to a plurality of spaced paths, means for continuously deiecting said rst named projected light beams along a series of parallel transverse paths equal to the length of the eld of view interspersed between said iirst named paths produced by said initial change in the path of said light beams, and a screen positioned in the path of said last named reflected light beams for producing a visible image of a television subject.

9. In a television scanning system, -a light source, means for projecting the light issuing from said source along a predetermined path, rotating means for continuously reiiecting said projected light beamsalong a plurality of spaced paths, means positioned in the path of said deflected light beams for successively changing the path of each projected light beam into -a plurality of adjacent parallel lines each of elemental width and equal to the length of the eld of view interspersed between the said group of spaced light paths, and a screen means positioned in the path of all of said light beams for producing a Visible image thereon when illuminated successively by all of said paths of light.

l0. In a television scanning system, a light source, means for projecting the light issuing from said source along a predetermined path, a rotating disk means positioned in the path of said projected light beams for successively projecting said light beams along a plurality of spaced paths, means positioned in the path of said light beams projected by said disk for controlling said projected light beams and tracing the same along a plurality of adjacent paths each of elemental width and of a length corresponding to that of one dimension of the picture subject and interspersed between said first named spaced paths, and a screen positioned in the path of all said reflected light beams so as to produce a visible image when all of said light beams are successively traced across the same.

11. In combination, a rotary scanning disk for tracing a series of separated paths oi' light, and a plurality of fixed reflecting bodies in the path of each separate light path for so directing each successive path of light traced by the said rotary scanning disk as to form a plurality of parallel interspersed light paths each of elemental width and equal in length to one dimension of the picture.

12. In combination, a rotary scanning element for tracing a series of separated paths of light, and a plurality of xed reiiecting bodies inclined with respect to each other in two planes and arranged in the path of each of the separated scanning paths for so directing each successive path of light traced by the rotary scanning element as to form a plurality of parallel interspersed light paths each ci elemental width and equal in length to one dimension of the picture.

13. In a television system, a rotary scanning element and a iiXed independent means cooperating therewith for so directing the scanning beams from said scanning element as to successively distribute each scanning beam over a plurality of parallel paths each of elemental width and equal in length to one dimension of the picture occupying the space between the successive paths normally traced by the scanning beam.

14. In a television system, a rotary scanning disk for tracing a set of paths of lightacross a `plurality of adjacent parallel paths, each of elemental Width and equal in-length to one dit mension of the picture occupying the spacer between the successive pathsy normally traced by the scanning beam.

15. The method of'television scanning which includes directing light from a source in a single `beam,rdirecting the beam arcuately in sequence 2,011,271v i t 5 along a series of spaced light paths of a number materially less 'than sufficient to obtain sharp detail in image reproduction across a predetermined area, and progressively reflecting the beam in sequence along different parallel paths each equal in length to one dimension of a field of View and each of elemental Width during each arcuate motion for causingtincreased detail in image reproduction by interspersing additional light paths Within the area between initially 10 traced arcuate light paths.

BERNARD CIOFFARI. 

